Ptosis Overview and Causes

Study Notes

Ptosis

Definition: Drooping of the upper eyelid that covers more than the upper 1/6 (or 2 mm) of the cornea.
Causes:
- Congenital: Present at birth.
- Acquired: Develops later in life.
  - Neurogenic: Nerve problems affecting the eyelid muscles. - Oculomotor nerve palsy: Paralysis of the levator muscle. - Sympathetic paralysis: Paralysis of Muller's muscle.
  - Myogenic: Muscle problems affecting the eyelids. - Myasthenia gravis: Autoimmune disease causing muscle weakness. - Muscle dystrophy: Genetic disorder causing muscle degeneration.
  - Apponeurotic: Problems with the tissue that connects the eyelid to the eye socket. - Involutional ptosis: Age-related weakening of the eyelid muscles. - Post-operative ptosis: Drooping after eyelid surgery.
  - Traumatic: Injury causing eyelid drooping. - Mechanical: Weight of a chalazion (cyst) or tumor on the eyelid. - Hysterical ptosis: Rare form of ptosis associated with psychological factors.
Examination:
- History: Age of onset, history of fever, trauma, and family history.
- Exclude pseudoptosis: Drooping due to other causes, such as:
  - Microphthalmos: An abnormally small eye.
  - Enophthalmos: An eye that is sunken into the socket.
  - Contralateral lid retraction: The other eyelid is pulled upward.
- Measurements:
  - Marginal reflex distance (MRD): The distance between the eyelid margin and the corneal light reflex, estimating ptosis severity.
  - Levator function: How much the eyelid can move, measured in millimeters.
    - Good: 12 mm.
    - Fair: 6-11 mm.
    - Poor: 5 mm or less.
- Associated signs:
  - Jaw-winking (Marcus Gunn’s phenomenon): The drooping eyelid rises when the jaw moves.
  - Superior rectus weakness: Weakness of the muscle that moves the eye upward.
  - Epicanthus: A fold of skin covering the inner corner of the eye.
Surgical treatment of Ptosis:
- Indications:
  - Congenital ptosis: Present at birth.
  - Acquired ptosis: When the cause cannot be treated or treatment has failed.
- Contraindications:
  - Complete third nerve paralysis with diplopia: Double vision due to paralysis of the third cranial nerve.
  - Corneal anesthesia or absence of Bell’s phenomenon: Lack of corneal sensitivity or inability to close the eyelids when the eyes are closed.
- Time of surgery:
  - Severe ptosis: Surgery as early as possible to avoid amblyopia (lazy eye) if the pupil is covered.
  - Mild-moderate ptosis: Surgery delayed until preschool age (5 years) if the vision is not affected.
- Types of surgery:
  - Fasanella Servat operation: For mild ptosis due to weak Muller muscle. Resects the Muller muscle through a conjunctival approach.
  - Levator resection operation: For mild to moderate ptosis due to weak levator muscle.
    - Skin approach: Everbusch’s operation.
    - Conjunctival approach: Blascovics operation.
  - Sling operations: For severe ptosis when the levator muscle is paralyzed. Lifts the eyelid using:
    - Fascia lata: Tissue from the thigh.
    - Mersaline mesh: Synthetic material.
    - Frontalis muscle sling: Uses muscles in the forehead.